Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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66757-37
This invention relates to an apparatus for stretching a
plastic raw material, particularly to an apparatus for stretching
plastic dough having viscoelasticity, such as bread dough or
confectionery dough. More particularly, it relates to such
apparatus whereby stretching can be performed without a complex
mechanism.
A prior art dough stretching apparatus is disclosed in
United States Patent No. 3,973,895. In the aforesaid prior art
apparatus, conveyors are arranged in series and driven at
progressively higher speeds, and a plurality of rollers, rotatable
about their axes and along an endless roller path, are disposed
above khe conveyors. However, in such prior art apparatus, the
movement of the rollers is achieved by a complex drive mechanism.
For example, a pair of chains is mounted to shafts of rollers, at
both ends of rollers, to connect the rollers along an endless
roller path. ~s the rollers are freely rotatably mounted to
respective shaftæ, the rollers can rotate about their axes and
~rogress along the endless roller path by virtue of the movement
of the chains. Accordingly, the prior art apparatus requires a
transmission mechanism to rotate rollers and a driving device to
cause the chains to progress, thereby requiring a large space for
these devices.
The present invention provides an apparatus for
stretching a plastic raw material by a simple mechanism.
In particular the present invention provides an
apparatus for stretching a plastic raw material, which comprises a
plurality of serially arranged conveyors and a plurality of
66757-37
rollers, in an endless roller path, positioned above the plurality
of conveyors, characterized in that shafts of the rollers are
provided with moving members of a linear motor, and that a stator
of the linear motor is positioned, spaced apart by a predetermined
distance from the moving members, along the endless roller path.
The present invention further provides an apparatus for
stretching a plastic raw material, which comprises a plurality of
serially arranged conveyors and a plurality of rollers, in an
endless roller path, positioned above the plurality of conveyors,
characterized in that a shaft of at least one of the rollers is
provided with a moving member of a linear motor; that a stator of
the linear motor is positioned, spaced apart by a predetermined
distance from the moving member, along the endless roller path;
and that connectiny means are provided to link the shafts of the
rollers with each other.
Conveyors are arranged in series. An upstream conveyor
receives a plastic raw material and conveys it to a downstream
conveyor. Above these conveyors are positioned a plurality of
rollers arranged in an endless roller path, which may be an oval
path having a straight portion at its bottom spaced apart from the
conveyors by a predetermined distance. The distance between an
upstream conveyor and the roller path may be greater than the
distance between a downstream conveyor and the roller path. The
rollers are freely rotatable about their shafts and are arranged
to progress along the roller path at a speed higher than any of
the conveyors, which are run in such a
speed relationship that an upstream conveyor is slower than a downstream
conveyor. The plastic raw material fed onto the conveyors is stretched by
the co-action between the rollers and the conveyors.
The driving force for the rollers is obtained by a linear motor or
a built-in motor mounted in the hol~ow portion within one or more rollers.
When the linear motor is used, each roller or at least one roller is provided
with a moving member, forming a portion of the linear motor, fixed to a shaft
about which the roller is made to rotate. The other portion of the linear
motor, i.e., the stator, is disposed along the endless roller path. The
movi.ng member is also called a reaction plate when the linear motor is a linear
induction motor. Further, various other types of linear motors can be used
in the present invention by using a primary member and a secondary member
of the linear motor either as a stator or a rotor, respectively. When a
built-in motor is utilized, rollers equipped with the built-in motors rotate
about their axes, while the rotation of the shafts about their axes is
precluded. In accordance with the present invention, complex mechanisms which
have hitherto been employed are not required, and a simple and reliable
composition of the apparatus can be achieved, which enables the speed control
required for stretching to be carried out without difficulty.
To secure the progress of the rollers on the endless roller path,
any suitable means may be employed. Especially in case only one roller is
equipped with a moving member, it becomes necessary to connect the rollers
by means of link arms.
The following is a description, by way of example, of certain
embodiments of the present invention, reference being had to the accompanying
drawings in which:
Figure 1 is a side elevation view showing a stretching apparatus
composed of two conveyors and a plurality of rollers of the present invention.
-- 3 --
Figure 2 is a cross-sectional view of the rollers provided with a
linear induction motor of a first embodiment of the present invention.
Figure 3 is a side elevation view showing the rollers, each roller
having a moving member of a linear induction motor, of the first embodiment
of the present invention.
Figure 4 is a side elevation view showing the rollers provided with
link arms according to a second embodiment of the present invention.
Figure 5 is a cross-sectional view of rollers, one of which is
provided with a built-in motor, of a third embodiment of the present
invention.
Figure 6 is a side elevation view showing rollers provided with
link arms of a third embodiment of the present invention.
A distributor 32 is taken oEf in the drawing.
The structure of a first embodiment of the present invention will be
described with reference to Figures 1 through 3. Figure 1 shows a stretching
apparatus comprising two conveyors 1 and 2 and a plurality of rollers 3.
plastic raw material, for instance, dough 11 is fed onto the conveyors in
the direction of the arrows. The conveyors may be belt-conveyors and arranged
in series. The downstream conveyor is run at a faster speed than the upstream
conveyor. the rollers 3 are arranged to run along an oval path, in the
clockwise direction in Figure 1, at a substantially higher speed than either
oE the conveyors. When the rollers are at the bottom stretch of the oval
path, the rollers are spaced apart from the conveyors so as to allow the passage
of the dough. When the dough is fed into the space between the rollers and
the conveyors, the rollers are made to rotate about their shafts, in the
counter-clockwise direction in Figure 1, while they advance at a speed
substantially greater than the progress of the dough, thereby stretching the
dough.
-- 4 --
The rollers 3 are Ereely rotatably mounted on shafts 4. Bearings 5,
in the form of a wheel of a diameter larger than the shaft 4, are mounted on
shafts 4 adjacent both ends of rollers 3. A pair of oval-shaped guides 8 are
disposed inside the endless roller path 12 to function as travel guides for
the movement of the bearings 5. The guides 8 are in turn mounted on the
frame of the apparatus.
A reaction plate 6 of a linear induction motor is fixed to the ends
of each of the shafts 4, and a stator 7 is disposed, along a plane parallel
to the endless roller path, leaving a predetermined space from the reaction
plates 6. The stator 7 is formed as the primary member of the linear induction
motor, and the reaction plates 6 and the stator 7 can act in combination as a
linear induction motor. The bearing 5 on the other end of each roller 3 is
inserted into a space between a guide 8 and the frame (not shown) so that the
rollers are retained in position. Rails 9 are disposed underneath and at both
ends of the rollers on the bottom stretch of the endless roller path 12 and are
in contact with the surfaces of the rollers. Since each roller is provided
with a reaction plate 6, each roller can move independently of and in unison
with the other rollers around the guides 8 when an electric current is supplied
to the stator 7, and, when the rollers come into contact with the rails 9,
they also rotate around their axes by the friction with the rails 9.
In operation, dough 11 is fed into the apparatus between a conveyor
belt 10 and the rollers 3 on the bottom stretch of the endless roller path 12.
The conveyors 1, 2 are run such that the downstream conveyor 2 is faster than
the upstream conveyor 1. The rollers 3 progress at a speed higher than the
conveyors 1, 2 while rotating about their axes. The rotation and progress of
the rollers are caused by the linear inductive action between the reaction
plates 6 on the rollers and the ring-form stator 7.
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~2~
A second embodiment of the present invention is shown in Figure 4,
in which each pair of adjacent rollers 20 are connected with a link arm 26.
The arm 26 has holes at both ends thereof to be rotatably mounted onto the
shaft 4 of each of the pair of rollers 20. The arm 26 which connects to
one roller of the pair is further connected by a similar arm to a third roller
next to the pair in a similar manner, except that the arm is mounted to the
shafts 4 at a position offset from the first arm 26. In this manner each
roller is connected to the adjacent rollers throughout the endless roller
path 12. In this embodiment, the rollers are made to move along the guides
8, even if only one roller is provided with a reaction plate 6.
The third embodiment of the present invention is shown in Figure
5 and 6. This embodiment is similar, in general composition, to the
second embodiment. In the second and third embodiment, dough
11 is fed into the apparatus between a conveyor belt 25 and the rollers 20
on the botl:om stretch of the endless roller path 12, and is stretched by the
co-action of the conveyors and the rollers in a manner similar to the first
embodiment. What differs here is the drive mechanism. At least one motor 21
is fixedly mounted within one of the rollers and an electric current is
supplied from a distributor 32 through electrodes 22 and 24. The roller 20 is
rotatably mounted on a shaft 23 and is made to rotate by the driving force of
the motor 21. The motor 21 is provided with a shaft (not shown), which
extends in the center of the motor, constituting a stator, and rotatably engages
the rest of the motor 21 constituting a rotor. The stator of the motor 21 is
fixed to the shaft 23, and the rotor of the motor 21 is fixed to the roller 20,
whereby the rotation of the roller 20 about the shaft 23 is effected when an
electric current is supplied to the motor 21.
As in the second embodiment, an arm 26 is mounted on each shaft 23
in the third embodiment and connects any pair of adjacent shafts. Thus, all the
rollers 20 are spaced apart from each other by the distance of an arm. ~ach
-- 6 _
arm 26 is connected to each shaft 23 in such a manner as to preclude a free
rotation of the shaft 23 about its axis, but care must be taken so that the
arm 26 can slightly rotate to permit its progress about the rounded ends of
the guides 31. In this arrangement, if a roller progresses along the
endless roller path, all the other rollers are made to progress simultaneously.
In this arrangement the rollers can be rotated by the motor 21 around the
shafts 23. A pair of wheel-form bearings 30 are fixedly mounted on both
ends of the shaft 23, one on each end, and come into contact with an oval-
form guide 31 provided near each end of the shaft 23. The bearings 30 serve to
cause the shafts 23 to move around the guides 31.
A pair oE friction wheels 27 may be fixedly mounted on the shaft
23 on both sides of the roller 20. A pair of rails 23 are mounted on the
frame facing the friction wheels 27 in a frictional relationship so that
this arrangement helps cause the rotation of the rollers 20 about their axes
to change, by the frictional engagement between the friction wheels 27 and
the rails 28, into the movement of the rollers around the guides 31. In this
sense it is advantageous to have the rails and the friction wheels, but
even without them the apparatus of this embodiment still functions, because
the frictional contact of the rollers 20 with the dough 11 and the rotation
of the ro]lers 20 makes the rollers progress. In the aforementioned
embodiments, the speeds of the linear motor and the built-in motor are easily
controlled in the usual manner, thereby achieving desired stretching effects.
Although the aforesaid embodiments of the present invention use an oval path
as a passage for the rollers, any other endless roller path, for instance, a
circular roller path, may be used.
Furthermore, although in the aforementioned embodiments the plastic
raw material to be stretched is plastic dough, such as bread dough or
confectionery dough, the apparatus of the present invention is in no way
limited to the stretching of such a food material, but may also be applied
to stretching any material in other industries.
The plastic raw material stretching apparatus of the above
structure obviates the need for a complex device such as that employed in the
prior art dough stretching apparatus. Also, since the apparatus of the
present invention is so constructed that a plurality of rollers are provided
with linear motors or built-in motors, which can be easily and securely
operated, stretching of the plastic raw material can be very easily
controlled,
